Here is the full list of all 51 Disgaea 3: Absence of Justice (EU) trophies - there are 42 bronze, 5 silver, 3 gold and 1 platinum.
Get all other trophies.
Find Axel in the Item World.
Do over 10,000,000,000 damage.
Defeat the Baal Pirates in the Item World.
Defeat the Prinny Pirates in the Item World.
Steal from all the Innocents and treasure boxes while Reverse Pirating.
Steal from all the Innocents while Reverse Pirating.
Defeat the 10 Gents Pirates in the Item World.
Beat floors 1 to 100 in a Land of Carnage Item World without exiting.
Get all the Reverse Pirating treasure boxes.
Play for over 10 hours without stopping.
Do over 100,000,000 damage.
Defeat the Red Pirates in the Item World.
Defeat the Kit Cat Pirates in the Item World.
Defeat an enemy with 10 combos or more.
Counter Attack over 10 times.
Get a Trophy from a Trophy Shop on the 90th floor.
Defeat the Shinsengumi in the Item World.
Defeat the Boney Pirates in the Item World.
Defeat the Element Pirates in the Item World.
Defeat the UFO Pirates(?) in the Item World.
Defeat the Horizon Pirates in the Item World.
Defeat the Cowboy Pirates in the Item World.
Defeat the Pirate Club in the Item World.
Defeat the Asian Pirates in the Item World.
Defeat Donnax2 Pirates in the Item World.
Defeat UFO? in the Item World.
Defeat Z Pirates in the Item World.
Talk to the Cat God at the top of the Treasure Tower.
Defeat the Garden Pirates in the Item World.
Get all the treasure boxes in the Treasure Room in the Item World.
Defeat the Ghost Pirates in the Item World.
Defeat the Pirate Cleaners in the Item World.
Defeat the Sports Pirates in the Item World.
Defeat Wise Innocents in the Item World.
Defeat the Cheerates in the Item World.
Defeat Lucky Pirates in the Item World.
Magichange 5 times in a battle.
Do over 1,000,000 damage.
Beat floors 1 to 100 in an Item World without exiting.
Defeat Eryngi Pirates in the Item World.
Accomplish over 255 combos in battle.
Force the Student Council to approve your Home Room request.
Defeat an enemy with a 10 story tower.
Clear Geo Blocks with 10 color changes in a row.
Receive 9 times and move over 60 panels.
Receive 4 times and move over 20 panels.
Clear Geo Panels with 5 color changes in a row.
Capture an enemy during battle.
Jump inside Evil Academy 100 times.
Get hit by ABC Gum.